Method for interaction of a data carrier with an end device

ABSTRACT

A method is provided for interaction of a portable data carrier with an end device. The data carrier comprises a transducer arrangement having at least one or a set of capacitive transducer elements which are arranged on or in the data carrier at defined positions in relation to the geometry of the data carrier, at least one contactless interface, and a dedicated energy supply. The end device comprises a capacitive display screen having a touch-sensitive display, wherein the data carrier generates via the capacitive transducer elements signals which, when the data carrier is placed onto the display screen, are picked up by the display screen of the end device and evaluated as input signals through the end device.

BACKGROUND

This invention relates to a method for interaction of a portable datacarrier, such as e.g. a chip card, a value document, a bank note havinga chip, an identification card, a payment card, an admission ticket orthe like, with an end device. An end device is understood to be e.g. acomputer, a notebook or laptop, a cash register of a cash registersystem, or a hand-held unit, such as e.g. a mobile phone, a tablet PC ora checking unit. The invention furthermore relates to a portable datacarrier as well as an end device of the above-designated kind. Further,the invention relates to a system for interaction of a portable datacarrier with an end device.

Methods are known wherein a security element of a portable data carrieris checked by being placed on a display screen of an end device. WO2009/019038 A1 describes the check of a data carrier which comprises awindow element configured as a light-transmissive region. In the windowelement an information item is configured in the form of a visible ornon-visible structure. For verification of the data carrier there isemployed a display screen of a computer, i.e. a conventional PC displayscreen or the display screen of a hand-held unit. To carry out averification of the data carrier, the window element with the structureinformation item configured therein is placed over a certain region ofthe display screen. On the display screen there is effected a displaywhich is correlated with the structure information item in the windowelement of the data carrier. Through the superimposition of the twopartial information items, a hidden information item becomes visible inthe window element of the data carrier, by which the data carrier isverifiable.

The operability of this security concept requires a sufficiently exactsuperimposition of window element and displayed information item on thedisplay screen. Furthermore, the described procedure is not suited forfinding the kind or the type of the data carrier to be verified inautomated fashion. If the data carrier is for example a bank bill havinga window element, it is unknown to the end device which bank bill islying on the display screen for verification.

CN 101819623 A discloses a storage data carrier having an IC which has aset of capacitive connecting points by means of which it can be read outby a reading device having a touch-sensitive display screen. One pair ofconnecting points serves for supplying energy to the data carrier, afurther pair for the readout of information stored on the data carrierthrough the reading device. This solution simplifies the handling of astorage data carrier upon the readout of information. However, therealization of a capacitive energy supply is elaborate.

SUMMARY

It is an object of the present invention to state a method that solvesthe above-mentioned problems and simultaneously enables a greaterflexibility upon the interaction of a portable data carrier with an enddevice. A further object of the present invention is to state a datacarrier and an end device that enable a flexible and secure interactionwith each other.

These objects are achieved by a method according to the features ofclaim 1 as well as a data carrier, an end device and a system accordingto the features of the further independent claims. Advantageousembodiments can be found in the dependent claims.

The invention provides a method for interaction of a portable datacarrier with an end device having a capacitive display screen. Aportable data carrier is understood here to be in particular a chipcard, a value document, a bank note having a chip, an identificationcard, a payment card, an admission ticket and the like. An end devicefor the purposes of the invention is e.g. a computer, a notebook orlaptop, a hand-held unit, such as e.g. a mobile radio device, a tabletPC, a cash register of a cash register system, etc.

The interaction preferably occurs, on the one hand, in such a way thatan end device determines the exact position of a data carrier on thedisplay screen and generates a display which is exactly coordinated withsaid position. There can thus be effected for instance a textual displaywhose alignment corresponds exactly to that of a principal axis of adata carrier.

In a preferred embodiment, there is further set up within the frameworkof the interaction a back channel from an end device to a data carriervia which the end device can send data to the data carrier, so as toenable a bidirectional communication between a data carrier and an enddevice.

The data carrier comprises a transducer arrangement having at least oneor a set of capacitive transducer elements which are arranged on or inthe data carrier at defined positions in relation to the geometry of thedata carrier.

A transducer element of the data carrier is understood to be anadditional capacitive area which is connected to a drive apparatusconfigured as an integrated circuit (integrated chip, IC). Driving thetransducer elements enables signals to be generated which are picked upand evaluated as input signals by the display screen of the end device.By the transducer elements being operated as sensors, and the displayscreen being suitably driven, a back channel can be set up from an enddevice to a data carrier.

The data carrier further comprises an interface for communication withan end device, preferably a contactless interface. In particular in theembodiment as a bank note, the interface is preferably configured as apurely contactless interface.

The data carrier further comprises a dedicated energy supply, whichmakes available, inter alia, the energy for operating the transducerarrangement. The energy supply works independently of the transducerarrangement. It is expediently configured in the form of an autonomousenergy supply, e.g. as a battery, or is effected via the contactlessinterface.

The data carrier can also comprise an additional contact-type interface.Such data carriers having a contact-type and a contactless interface aredesignated dual-interface data carriers; they typically comprise acontact pad and a coil.

The end device comprises a capacitive display screen having atouch-sensitive display. Display screens of this kind are nowwidespread, being used primarily in high-performance mobile phones(“smart phones”) or in tablet PCs. Capacitive display screens utilizethe rate of change of applied voltages on respective sensor areas of thedisplay screen. The surface of a glass substrate of the display screenconsists here of capacitors which change their value depending on thetouch of the finger. This change is ascertained and converted intocoordinates of the display screen by a logic coupled with the displayscreen.

According to the invention, the data carrier generates signals via thecapacitive transducer elements, which signals, when the data carrier isplaced onto the display screen, are picked up by the display screen ofthe end device and evaluated as input signals through the end device.Through evaluation of the signals of the transducer elements the enddevice derives the exact position of the data carrier on the displayscreen and performs at least one action which is based on the knowledgeof the exact position of the data carrier on the display screen. Theenergy for driving the transducer elements is made available here via acontactless interface or stems a dedicated energy supply of the datacarrier.

The invention further provides a data carrier for interaction with anend device. The data carrier comprises a transducer arrangement havingat least one or a set of capacitive transducer elements which arearranged on or in the data carrier at predefined positions in relationto the geometry of the data carrier. Further, the data carrier comprisesat least one contactless interface and a dedicated energy supply.

The data carrier can be present in the form of a dual-interface card, inwhich case it additionally has a contact-type interface besides thecontactless interface. It can also be provided to equip the data carrierwith an NFC unit for a near-field communication (NFC), which, besidesmaking available a data transfer channel, can also serve to supplyenergy to the components of the data carrier.

The invention further provides an end device for interaction with a datacarrier according to the invention. The end device, e.g. a computer, alaptop or notebook, a tablet PC, a mobile phone, a cash register of acash register system, etc., is configured for deriving the exactposition of the data carrier on the display screen through evaluation ofthe signals of the transducer elements of the data carrier according tothe invention.

Further, the invention proposes a system for interaction of a portabledata carrier with an end device, which system comprises at least onedata carrier according to the invention as well as at least one enddevice according to the invention.

In an embodiment that is especially easy to realize technically, thedata carrier comprises a contact-type interface having several contactpads. According to this embodiment, the data carrier is configured as adual-interface data carrier. The contact pads of the contact-typeinterface are employed according to the invention as capacitivetransducer elements on which the signals for the display screen aregenerated. This requires that the data carrier is placed onto thedisplay screen with the contact-type interface downward, so that signalsof the contact pads serving as capacitive transducer elements can bedetected and evaluated as input signals by means of the capacitivedisplay screen of the end device.

Selectively, the capacitive transducer elements are driven individuallyor jointly. The transducer elements are arranged at defined positions inrelation to the geometry of the data carrier. The transducer elementscan be provided so as to be distributed over the area of the datacarrier. They can likewise be provided on or in the data carrier in aspatially concentrated manner and, in relation to individual components,in a defined manner relative thereto.

For driving the transducer elements, a drive apparatus causes changes ofcharge, in particular in an order of magnitude in a range from 2 pF to 1nF, on the transducer elements. The energy required for driving thetransducer elements is taken from the data carrier's internal energysupply or transmitted from the end device through the contactlessinterface via inductive coupling. A sufficient energy supply is reliablyobtained here with known end devices, such as mobile radio end devices,tablet PCs and the like, even when the antenna of the end device isarranged on the side of the end device facing away from the displayscreen.

In a further expedient embodiment, the data carrier comprises a windowelement in relation to which the transducer elements are arranged atpredefined positions on or in the data carrier. A window element isunderstood here to be a light-transmissive region, as is described in WO2009/019038 A1 from the applicant. The content of this print isincorporated in the description of this invention by reference.According to the definition given in WO 2009/019038 A1, a firstinformation item is arranged in the light-transmissive region. A secondinformation item is displayed at least in certain regions in theseparate display screen of the end device. Either in the first or thesecond information item or also in both information items there ishidden a further information item which is not, or only hardly,recognizable and/or readable for a viewer without auxiliary means. Averification of the data carrier is effected by the first informationitem in the translucent region of the data carrier being laid over thesecond information item of the display screen and the hidden informationitem becoming recognizable and/or readable as a pattern and/or as ametamerism.

In the method according to the invention it is provided that the enddevice derives the exact position of the data carrier on the displayscreen through evaluation of the signals of the transducer elements, andoutputs on the display screen a content information item which iscorrectly positioned relative to the data carrier and the windowelement. An advantage of this procedure is that the superimposition ofwindow element of the data carrier and display on the display screen nowno longer needs to be performed manually. Instead, the position of thewindow element with the first information item contained therein isascertained automatically by the display screen on the basis of thetransducer elements arranged in a defined manner in relation to thewindow element. The superimposition of first and second informationitems in the window element and the display screen can thus be effectedmore precisely.

The signals generated on the display screen of the end device caninvolve content information items. They allow the end device inparticular to derive the exact position of the data carrier or of thewindow element arranged in the data carrier. On the basis of theascertained position of the window element, the end device can generateon its display screen a display that is in exactly correctly positionedrelative to the window element. With a data carrier having a windowelement, the existence of a correctly positioned display constitutes fora user an essential feedback that the data carrier and the displayscreen or end device work together. With bank notes having a windowelement, the display allows in particular an authenticity check. Thenecessary, end-device-side adjustment to the data carrier can beeffected through corresponding software, for instance through thestoring of applets (i.e. a corresponding application).

In a further embodiment, there is effected via the transducer elements asignal exchange from the display screen to the data carrier, by thetransducer elements being operated as sensors and signals beinggenerated location-dependently through the display screen, which signalsare detected by the transducer elements operated as sensors and areevaluated as input signals through the data carrier. This enables a backchannel to be realized from the end device via its display screen to thedata carrier. The transducer elements 11, 12, 13, 14 can, in so doing,be individually addressed and thus a fast and more complex signaltransmission be realized.

In an especially simple embodiment of the back channel, the latter canbe realized by the capacitive drive of the display screen of the enddevice being switched on and off as a whole and these switch-on and -offoperations being detected by the transducer elements. In so doing, thedisplay screen can remain activated for displaying information, only thedrive for user input being deactivated. The actual signal transmissioncan be realized here e.g. through the ratio of switch-on time to totalduration of a specified time unit, with switch-on times smaller than acertain reference value being rated e.g. as logical “0” and switch-ontimes greater than the reference value as logical “1”, thereby enablingsignals to be transmitted from the end device to the data carrier.

The back channel can, in an advantageous alternative embodiment variant,also be realized through cooperation of an acceleration sensor formed inthe data carrier with a vibration apparatus configured in the end deviceand acting on the display screen. Through corresponding drive of thevibration apparatus there is generated a signal which is detected by theacceleration sensor.

The set-up of the back channel on the end device can frequently beadvantageously effected through a software adjustment, without anyhardware changes being required. For example, an applet can be madeavailable for this purpose in the data carrier, the applet beingtransferred from the data carrier to the end device. The use of the backchannel from the end device to the data carrier is of practicalimportance in particular for data carriers configured as cards, such ase.g. payment cards, admission tickets, value cards, etc.

In an advantageous development, the data carrier according to theinvention is equipped with a consent apparatus which has the effect thata signal transmission between data carrier and display screen, when thedata carrier is placed on, is effected only when a user confirms itthrough a certain action. Expediently, the consent apparatus cancomprise in particular a back contact area via which a user closes acircuit by simultaneously touching an outside contact area connected tothe display screen, the closed circuit being a requirement for thepossibility of changes of capacitance between data carrier and displayscreen and thus for a signal transmission.

Besides a fast and exact check of the authenticity of a data carrier, inparticular a bank note, by means of an end device configured as achecking unit, the method according to the invention allows a number ofbasic value transactions. As described in the introduction, theserequire the data carrier to be placed onto the capacitive display screenof the end device.

In a first variant, for carrying out a security-critical transaction onthe end device, transactions are transferred to a computer whichencrypts the transaction data as an image with a key specific to thedata carrier and transfers them to the end device together with atransaction number via a separate channel, the image-encrypted databeing displayed on the display screen of the end device. The separatechannel can be e.g. an SMS (short message service). Expediently, adecryption of the image-encrypted data is effected only in the case ofcorrectly positioned superimposition of the window element with theimage-encrypted data displayed on the display screen.

For carrying out the value transaction according to the first variantthere is required a data carrier according to the invention having atransducer arrangement and an optional window element.

In a second transaction variant, the data carrier does not need to havea window element. For carrying out a security-critical transaction onthe end device according to a second variant, transaction data aretransferred from the end device to the data carrier via the contactlessinterface.

In an alternative, third variant using a data carrier having atransducer arrangement and a back channel, for carrying out asecurity-critical transaction on the end device, transaction data aretransferred to the data carrier via the transducer elements of the datacarrier.

In the second and third variants it can further be provided that throughthe data carrier a transaction number specific to the transaction isgenerated and transferred selectively via the contactless interface orthe transducer elements to the end device, which transfers thetransaction data together with the transaction number to a computer forfurther processing, in particular via a secure channel.

If the data carrier has a window element, the latter can be utilized ina simple manner for proving the operability of the data carrier, by e.g.the transaction data rendered on the display screen of an end devicebeing so aligned that they appear exactly in the window element of thedata carrier. Such an alignment is possible independently through thedata carrier only when the transducer elements of the data carrierdriven through the data carrier function properly. This functionalitythen constitutes proof that the data carrier is working in the expectedmanner.

The transfer of the transaction data can be effected here via thecontactless interface, e.g. via the NFC interface. Via the back channelthere is effected an authentication between the data carrier and the enddevice.

In a further variant, an authentication between the data carrier and theend device can also be effected via the contactless interface, e.g. theNFC interface. If a data carrier has an NFC interface, the latter can beprovided in addition to another contactless interface. The two describedvariants are expedient in particular when the end device has a speciallysecured runtime environment. Such a secure runtime environment of a datacarrier is e.g. the operating system MobiCore from the applicant, whichis employed in secure runtime environments of data carriers. As a secureruntime environment there can be employed e.g. an ARM® Trust Zone®.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereinafter be explained more closely on the basis ofexemplary embodiments. The representations in the figures areschematized for the sake of better comprehension and do not reflect theactual conditions. In addition, the described embodiments are reduced tothe essential core information for the sake of clarity. The proportionsshown in the figures likewise do not correspond to the relationsexisting in reality and serve solely to improve the clearness. There areshown:

FIG. 1 a schematic representation of a data carrier according to theinvention in the form of a card,

FIG. 2 a schematic partial representation of an end device having theelements essential to the invention,

FIG. 3 a data carrier according to the invention in the form of a banknote,

FIG. 4 a schematic representation of the sequence of a value transactionwhile employing the method according to the invention, and

FIG. 5 a schematic representation of a consent apparatus.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

FIG. 1 shows a first exemplary embodiment of a portable data carrier 1according to the invention. The portable data carrier 1 is basically acomputer with a reduced overall size and range of resources, which has amicrocontroller and at least one interface for communication with anexternal device. It frequently possesses no, or only a rudimentary,dedicated user data output. The microcontroller typically possesses anoverall size of a few mm² and, through its small overall size alone, isgreatly limited in its performance both in terms of data processingpower and in terms of storage capacity in comparison with conventionalPCs. Its outer construction form is so designed that it can be easilycarried by a user at any time. Typical embodiments of a portable datacarrier are for instance a chip card (card), a payment card, anadmission ticket or the like. The portable data carrier can also berealized in the form of a bank note, a passport or another valuedocument.

In a first embodiment, the data carrier 1 is configured by way ofexample as a so-called dual-interface card and has a contactless as wellas a contact-type interface for communication with an end device (notrepresented in FIG. 1). The contactless interface is represented by anantenna 36 and an NFC (near field communication) circuit (chip) 34. Thereference sign 38 designates a contact element of the contact-typeinterface. In its proper function the contact element is basicallyirrelevant for the employment of the data carrier 1 as proposed here,however.

Reference sign 32 represents a unit for supplying energy to the datacarrier. In the exemplary embodiment of FIG. 1 it derives its energyfrom the NFC chip 34. That is to say, the energy supply is effectedinductively via the antenna 36. Alternatively, the energy supply 32 canalso be configured in the form of an autonomous energy source, e.g.through a battery or through an accumulator. Likewise, the energy supply32 can be formed through a solar cell which can be driven throughambient light or in particular through light emitted by a display screenof an end device; the light emission through an end device can beeffected for the solar cell in a targeted manner, e.g. throughgeneration of light flashes. Between the NFC chip 34 and the contactelement 38 a data exchange can take place. If a battery, an accumulatoror a solar cell is used, there is no need for a contactless interfaceinsofar as it serves for energy transmission.

The data carrier 1 further comprises a transducer arrangement 10 havingat least one capacitive transducer element, there being provided fourcapacitive transducer elements 11, 12, 13, 14 by way of example in theembodiment shown in FIG. 1. The transducer elements 11, 12, 13, 14respectively comprise, on the one hand, a capacitor 121, 122, 123, 124having two capacitive areas, one of which is respectively connected to adrive apparatus 30; on the other hand, the transducer elements 11, 12,13, 14 respectively comprise a contacting area 111, 112, 112, 114. In afirst embodiment, the contacting area 111, 112, 112, 114 is arrangeddirectly on an upper side of the data carrier 1, so that, when the datacarrier 1 is placed on, there is a direct contacting with the surface ofthe glass substrate of the display screen 52. In an alternativeembodiment, a protective foil is arranged over the contacting area.

The drive apparatus 30 can be realized e.g. as part of a single chipcontroller for chip cards or be configured as a separate component. Itis connected to the energy supply 32. The drive apparatus 30 caninfluence the charge state of the transducer elements 11, 12, 13, 14 ina targeted manner and in particular supply energy. It draws the requiredenergy from the energy supply 32. The transducer elements 11, 12, 13, 14are arranged in or on the data carrier 1 at defined positions inrelation to the geometry of the data carrier 1, but also in relation toa window element 20 optionally provided in the data carrier 1. By way ofexample the transducer elements 11, 12, 13, 14 are placed around thewindow element 20 in FIG. 1. The number and arrangement of thetransducer elements 11, 12, 13, 14 can also deviate from the shownrepresentation.

In the embodiment shown in FIG. 1, separate transducer elements 11, 12,13, 14 are represented. However, in the dual-interface card illustratedby way of example, the contact pads—not specifically represented—of thecontact element 38 could also be employed especially advantageously ascontacting areas of the transducer elements 11, 12, 13, 14.

The transducer elements 11, 12, 13, 14 can selectively be drivenindividually or jointly, the drive being dependent on the employment ofthe data carrier.

The data carrier represented in FIG. 1 interacts with a capacitivedisplay screen 52 of an end device 50 whose basic elements relevant hereare represented very schematically in FIG. 2. The capacitive displayscreen 52 is driven by a display screen control unit 55. The displayscreen control unit 55 at the same time evaluates capacitive changesbetween the display screen 52 and an opposing element, in particular afinger or a transducer element of a data carrier 1, as indicated by thecapacitor symbol. It can further be provided that the capacitive displayscreen 52 is connected electrically via a suitable connection 51 to anoutside contact area 53, which lies on an outer side of the end device50 such that it can be touched by a user. The outside contact area 53can be realized in a simple manner through a metallic housing of an enddevice 50, and the connection 51 can be effected through mounting meansor connection means. Many end devices 50 have a corresponding device,without it having to be specially set up. End devices 50 regularly havefurther parts and components which are not important to the inventiondescribed here, and therefore not shown.

The end device 50 can be e.g. a publicly accessible terminal. Inaddition, the end devices 50 may, however, also generally be computers,laptops, netbooks, tablet PCs, mobile radio end devices, PDAs and thelike, which are meanwhile frequently equipped with capacitive displayscreens 52.

In a capacitive display screen 52 the display screen surface iscontinuously scanned for capacitive changes with high local resolution.For this purpose a suitable known method is used. According to one knownmethod, test signal sequences consisting of signal packets withdifferent amplitudes are generated location-dependently under thecontrol of the display screen control unit 55. Changes of the testsignal sequences through external influences, in particular throughcapacitive influencing through finger touch, are detected by the displayscreen control unit 55. Such a change can also be caused through thetransducer elements 11, 12, 13, 14 represented in the data carrier 1,there being added to an existing capacitor value of the capacitivedisplay screen 52 a further one through the transducer elements 11, 12,13, 14.

According to the invention, the data carrier 1 generates signals via thecapacitive transducer elements 11, 12, 13, 14, which signals, when thedata carrier is placed onto the display screen 52, are picked up by thedisplay screen 52 of the end device 50 and evaluated as input signalsthrough the end device 50.

In so doing, the data carrier 1 is placed onto the display screen 52such that the contacting areas 111, 112, 112, 114 of the transducerelements 11, 12, 13, 14 lie directly on the display screen 52. The driveof the transducer elements 11, 12, 13, 14 is effected by the driveapparatus 30 causing minimal changes of charge in the connectedcapacitive areas of the transducer elements 11, 12, 13, 14, and thusminimal changes of capacitance of the transducer elements 11, 12, 13,14, through a controlled supply of energy from the energy supply 32. Theorder of magnitude of the changes of charge expediently lies in a rangeof 2 pF to 1 nF, but changes of charge of less than 2 pF up to 1 pF arealso already technically exploitable. In principle, greater valuessupport the quality of the signal transmission, while smaller valuesenable smaller construction forms and are suited in particular e.g. forrealizing the invention in bank notes. The energy for driving thetransducer elements 11, 12, 13, 14 can be obtained by the data carrier 1from the end device 50 via the antenna coil 36. A sufficient energysupply is obtained even when the end-device-side antenna is arranged onthe device's back side facing away from the display screen 52.

The end device 50 detects e.g. by means of test signal sequences, asexplained hereinabove, the changes of charge caused in the transducerelements 11, 12, 13, 14 and ascertains therefrom the exact position ofthe transducer elements 11, 12, 13, 14 on the display screen 52. Becausethe transducer elements 11, 12, 13, 14 are arranged at a given distanceor in a given position relative to the window element 20, the end devicecan ascertain the exact position of the window element 20 or the exactposition of the data carrier 1 on the display screen on the basis ofthis information. For carrying out the determination of position therecan be provided in the end device 50 a corresponding softwareapplication, e.g. an applet, which is executed by the display screencontrol unit 55.

It can be provided that graphical or alphanumeric control informationoutput on the display screen 52 displays to the user in which directionthe data carrier 1 must be shifted relative to a current position of thedata carrier 1 in order that a position determination can be effected.

That the detection of the position of the data carrier 1 on the displayscreen 52 has been successfully carried out is communicated to the user.For this purpose, the transducer elements 11, 12, 13, 14 can e.g. beactivated successively e.g. in the clockwise direction and there can beprovided e.g. a text output coordinated with the window element 20 andrepresenting an information item 54 shown in the display screen 52, inFIG. 1 for instance the word “TEST”. Upon successful detection ofposition the shown information item 54, i.e. for instance the word“TEST”, jumps into the region of the window element 20 in correctorientation. The orientation was ascertained from the activationsequence of the transducer elements, in the clockwise direction.

The actual signal transmission can be realized here e.g. by the ratio ofswitch-on time to the total duration of a specified time unit, e.g. aswitching period, with switch-on times smaller than a certain referencevalue being rated e.g. as logical “0” and switch-on times greater thanthe reference value as logical “1”. Through an even more exactresolution of the ratio of switch-on time to time unit it is furtherpossible to individually identify single transducer elements 11, 12, 13,14. Then it is possible to unambiguously recognize e.g. a transducerelement arranged on the top right in plan viewing on the basis of acertain longer or shorter ratio of switch-on time to time unit, so thata determination of the orientation of a data carrier 1 is unambiguouslypossible even when an even number of transducer elements is arrangedpoint- or axisymmetrically on the data carrier.

In an alternative possible embodiment, the word “TEST” could rotate inthe clockwise direction within the window element 20. The showninformation item 54 is of course not limited to representations ofwords, but can be an arbitrary graphical representation; the renditioncan of course also be effected statically.

In a very advantageous development of the invention it can be providedthat there is set up between display screen 52 and data carrier 1 viathe transducer elements 11, 12, 13, 14 a back channel via which channelthe end device 50 transmits signals to the data carrier 1.

A back channel can be realized by the transducer elements 11, 12, 13, 14being operated as sensors and the display screen 52 being suitablydriven. In this case the drive apparatus 30 is configured to detect thecharge states or changes of capacitance of the transducer elements 11,12, 13, 14 and to evaluate them as input signals. In a first embodimentof the back channel, location-related signals are generated for a datacarrier 1 placed on the display screen 52 through corresponding drive ofthe test signal sequences. For the formation of the test signalsequences the previously recognized position of the data carrier 1 isutilized. The transducer elements 11, 12, 13, 14 can in this way beindividually addressed and thus a fast and more complex signaltransmission be realized. The signals are detected by thedata-carrier-side transducer elements 11, 12, 13, 14 operated assensors.

Alternatively, the back channel can be realized e.g. by the displayscreen 52 being switched on and off as a whole and this being detectedby the drive apparatus 30 via the transducer elements 11, 12, 13, 14.The actual signal transmission can be realized here e.g. by the ratio ofswitch-on time to the total duration of a specified time unit, withswitch-on times smaller than a certain reference value being rated e.g.as logical “0” and switch-on times greater than the reference value aslogical “1”.

The set-up of the back channel on the end device 50 can be effectedthrough software, e.g. through an applet installed on the end device 50.The software can also be made available by the data carrier 1 and betransferred from the latter to the end device 50.

In an alternative embodiment, the back channel is realized through thecooperation of a vibration apparatus and an acceleration sensor.Vibration apparatuses are known for end devices, being frequently usedthere for alarming a user. Acceleration sensors are likewise known fordata carriers, where they serve e.g. for ascertaining changes ofposition in space. For realizing a back channel, the data carrier 1 isequipped with an acceleration sensor, and the end device 50 with avibration apparatus. The latter is driven e.g. intermittently throughcorresponding software, with a signal transmission being effectedthrough the ratio of on and off times.

To ensure that the placing of a data carrier 1 onto a display screen 52is effected by a user, in a further development a change between“touched” and “not touched” can also be evaluated using software or asoftware extension of an end device 50. As a result it can be ensuredthat a user has actively placed a data carrier 1 onto a display screen52, for instance onto a display screen 52 of a cash register device orpayment device. This method makes a relay attack impossible.

To ensure that a data exchange between a data carrier 1 and an enddevice 50 is effected deliberately, in an embodiment variant the datacarrier 1 can have a consent apparatus 40, as is representedschematically in FIG. 5. It comprises at least one back contact area 41which is formed on the back side of the data carrier 1 facing away fromthe transducer elements 111, 112, at least one electrical switch 42which is connected to the drive apparatus 30, and an electricalconnection 43, guided across the switch 42, between the back contactarea 41 and at least one of the transducer elements 111, 112.

The back contact area 41 can be based e.g. on graphite or carbon black,or consist of a conductive polymer, and expediently possesses a moderateelectrical conductivity with a resistance of <100 kΩ. The switch 42 isexpediently a transistor, a FET, a relay or a similar component. It canbe configured as a separate component or as an integrated part of themicrocontroller of the data carrier 1. The electrical connection 43 canbe realized e.g. by means of wires. One back contact area 41 can beconnected to one or several transducer elements 111, 112 via one orseveral switches 42, or there can also be provided several back contactareas 41 which are respectively connected to one or several transducerelements 111, 112 via an associated switch 42. The transducer elements111, 112 basically correspond in number and arrangement to thetransducer elements 11, 12, 13, 14 according to FIG. 1 but, unlike them,respectively comprise only one contacting area 111, 112 which isconnected to the switch or switches 42; the transducer elements 111, 112do not possess an additional capacitance like the transducer elements11, 12, 13, 14. The respective second capacitive area for realizing acapacitance is formed by the display screen 52. When the data carrier 1is configured as a contact-type chip card, the contacting areas 111, 112are for example expediently realized by the contact areas alreadypresent. The drive apparatus 30 can be surrounded by an encapsulation 45into which further ones of the stated components 42, 43, 111, 112 canalso be wholly or partly embedded.

The end device 50 has an outside contact area 53 which is electricallyconnected to the display screen 52 via a suitable connection 51.

The consent apparatus 40 functions as follows. In order that the driveapparatus 30 can cause a change of the charge state of the transducerelements 111, 112, it must drive the switch or switches 42. Moreover, anelectrical transition must be possible between transducer elements 111,112 and display screen 52. This requires a circuit with the transducerelements 111, 112 to be closed via the back contact area 41, the enddevice 50 and the display screen 52. For this purpose the user mustphysically touch the back contact area 41 of the data carrier 1, on theone hand, and simultaneously an outside contact area 53 of the enddevice 50 connected to the display screen 52, on the other hand. Via theuser's body a circuit is then closed, as indicated by the dash line,thereby enabling a charge flow between the transducer elements 111, 112and the display screen 52, and thus changes of charge.

A data carrier 1 configured as described hereinabove enables a datatransfer between the data carrier 1 and an end device 50 which is basedon the principle of generating via the capacitive areas of thetransducer elements 111, 112 electrical sinks which can be equated witha touch by a finger. The contacting areas of the transducer elements111, 112 behave passively—i.e. they are high-ohmic—on the capacitivearea of the display screen 52 as long as they are not connected to afixed potential. As long as the transducer elements 111, 112 are notactively driven by the drive apparatus 30, they are in so-calledtri-state. If the data carrier 1 possesses for instance contactelements, on the one hand, and a contactless interface, on the otherhand, and the data carrier 1 is in contactless operation, all inputsrealized via the contact elements are in tri-state. Using software it ispossible via the switches 42 for the drive apparatus 30 to switch thecontacting areas of the transducer elements 111, 112 to a fixedreference point—and thus end the tri-state. Through the change betweenthe two states a data carrier 1 lying on the capacitive display screen52 of an end device 50 can apply changing signal levels on thecontacting areas. These level changes are rated as a finger touch by thecapacitive display screen 52 and reported to the end-device-sideevaluation unit, i.e. for instance the display screen control unit 55. Asignal transmission can then in turn be realized for example via theratio of switch-on time to a certain time unit.

For verifying a represented information item there can be employed e.g.the method described in WO 2009/019038 A1.

FIG. 2 shows a second exemplary embodiment of a data carrier 1 accordingto the invention in the form of a bank note or bank bill. By way ofexample there is schematically represented a bill with a denomination20, which can basically be for instance a 20 euro bill, as indicated.The bank bill likewise comprises a window element 20 around which fourtransducer elements 11, 12, 13, 14 are again arranged merely by way ofexample. As in the preceding exemplary embodiment, the transducerelements 11, 12, 13, 14 are connected to a drive apparatus 30. Thelatter is coupled directly to an antenna 36 in the bank bill in order tomake available a wireless communication interface as well as an energysupply for the drive apparatus 30. The circuit in a bank bill is thusconstructed such that an energy withdrawal is effected directly andwithout decoupled voltage supply of an NFC field of an end device. Thisis possible because no independent NFC communication needs to beeffected. The drive apparatus is so constructed that a certaininformation sequence is effected on the transducer elements 11, 12, 13,14 per bank bill. For example, a switching element can alternatelyswitch on and off the capacitance of a transducer element and thus itscontact area.

Equipping a bank note with a window element 20 and a transducerarrangement 10 allows a fast and very exact check of the authenticity ofa bank note using a corresponding checking unit.

Equipping a data carrier with a transducer arrangement describedaccording to the invention and optionally a window element allows anumber of basic electronic transactions. The solution according to theinvention is suitable, inter alia, for executing transactions in which adata carrier 1 communicates with an end device 50 in order to carry outan electronic transaction via the end device 50 e.g. with a serverconnected via a basically insecure data network.

FIG. 3 illustrates, as an example of an electronic transaction, theinducement of the transfer of an amount of money on an end device 50from a user's account to an account of a service provider, representedby a server, by means of a data carrier 1 configured in the format of achip card; the chip-card embodiment is adopted here only for the purposeof description; other embodiments of the data carrier 1 are of coursepossible. The end device 50 has a capacitive display screen 52.

The transaction commences by the end device 50 generating informationabout the intended transaction on the display screen 52. By way ofexample there is represented on the capacitive display screen 52 aninformation item 54 communicating to the owner of the chip card 1 that atransaction performed by him has a value of e.g.

15.00 and is being performed with a service provider “xyStore” in theform of a server (not shown). In order to complete the transaction, theuser is requested by a display “Please present card” output on thedisplay screen 52 to place his chip card 1 onto the display screen 52 ofthe end device 50. The user thereupon places his chip card 1 onto thecapacitive display screen 52 and the transaction is executed asdescribed more closely hereinafter. In order that the execution ispossible, it can be provided that the user, by simultaneously touchingthe chip card 1 and the end device 50, at least temporarily establishesa physical contact between the two to thereby close a circuit. After thevalue transaction is carried out, the user is e.g. informed via thedisplay screen 52 that the transaction has been successfully completed:“Transaction completed”.

The exact execution of the transaction when the chip card 1 is placed ondepends on how chip card 1 and end device 50 are exactly equipped. Afirst embodiment variant is based on a chip card 1 which has atransducer arrangement 10 as well as a window element 20. The end device50 can be e.g. a mobile radio end device, a tablet PC or the like.

The transaction data are transmitted from the end device 50 to theserver of the service provider. The latter forms for the transactiondata a transaction information item specific to the transaction, forwhich a transaction number (TAN) will hereinafter be adopted by way ofexample, and subjects it to an image encryption executed with acard-specific window key. The image encryption has the effect that anunchanged graphical rendition of the image-encrypted transaction data ona display screen 52 is not readable. Likewise, the transaction data canalso be image-encrypted. The server sends the image-encryptedtransaction number and, where applicable, the image-encryptedtransaction data via a separate communication channel back to the enddevice 50, which displays them on its display screen 52. The separatecommunication channel can be e.g. an SMS. The window element 20 of thedata carrier 1 is configured for removing the image encryption, by areadable, understandable rendition of transaction number and, whereapplicable, transaction data being effected on the display screen 52only in the case of correctly positioned superimposition. Such anencryption/decryption can be realized in a simple manner for exampleusing a lens structure incorporated into the window element 20, whichdelivers a valid, readable image only when the graphical pattern to berendered is represented on the display screen 52 in a manner speciallycoordinated with the lens structure.

In a modification of the first embodiment variant there is used a chipcard 1 having a transducer arrangement 10 but not a window element. Thetransaction data are again transmitted to a server of a serviceprovider, who forms a transaction number (TAN) for the transaction dataand sends it via a separate communication channel back to the end device50, which displays it on its display screen 52. In contrast to the firstembodiment variant, there is no image encryption in this variant.Instead, the output of the transaction number and, where applicable, ofthe transaction data is effected in a certain relation to the chip card1. The end device 50 for this purpose first determines the exactposition of the chip card 1 on the display screen 52 and subsequentlyoutputs the transaction number and, where applicable, the transactiondata in coordination with the ascertained position such that they appearin a defined relation to the chip card 1 outside the area of the displayscreen 52 covered by the chip card 1. For example, the rendition of thetransaction number and, where applicable, of the transaction data can beeffected over a certain longitudinal edge of the chip card 1 in analignment parallel to the longitudinal edge. The rendition can moreoverbe coordinated with markings provided on the chip card 1. A deviatingalignment or a mismatch with the markings then indicates animpermissible, untrustworthy rendition.

In a second embodiment variant there is used a chip card 1 equipped onlywith a transducer arrangement, without a window element. The transactiondata are now transferred from the end device 50 to the chip card 1 via acontactless interface of the chip card 1, e.g. the NFC interface. Thechip card 1 thereupon generates e.g. a transaction number and sends itback to the end device 50 via the transducer elements. The end device 50finally transfers the complete data, consisting of transaction numberand transaction data, to a server for further processing.

A third embodiment variant is based on a chip card 1 which has atransducer arrangement as well as additionally a back channel. Via theback channel the end device 50 sends transaction data to the chip card.The chip card 1 thereupon generates e.g. a transaction number and sendsit back to the end device 50 via the transducer arrangement. The lattersubsequently passes it to the server of the service provider. If thechip card 1/data carrier 1 additionally has a window element, the lattercan serve in a simple manner to prove the operability of the chip card1, by the transaction data being so aligned that they appear exactly inthe window element.

In an embodiment variant with the same data-carrier design, the transferof the transaction data is effected not via the back channel, but via acontactless interface of the chip card 1, e.g. via an NFC interface 36,as indicated in FIG. 1. Via the back channel an authentication takesplace between the chip card 1 and the end device 50. An authenticationis expedient primarily when the end device 50 has a specially securedruntime environment, so that in particular the result of anauthentication performed by such a secure runtime environment istrustworthy. Such secure runtime environments can be realized e.g. on asecurity element that is integrated but basically autonomous in relationto an end device 50, said security element being for example a SIM card.

Such an authentication through a secure runtime environment is furtheralso expedient when the data carrier 1 does not enable a back channelvia the display screen 52. The data exchange is then effected e.g. via acontactless interface to the chip card 1 and via the transducerarrangement to the end device 50.

The invention claimed is:
 1. A method for interaction of a portable datacarrier with an end device, wherein the data carrier comprises atransducer arrangement having at least one or a set of capacitivetransducer elements arranged on or in the data carrier at definedpositions in relation to the geometry of the data carrier, and the datacarrier is supplied with energy; wherein the end device comprises acapacitive display screen having a touch-sensitive display, wherein themethod comprises placing the data carrier onto the display screen andgenerating via the capacitive transducer elements signals picked up andevaluated as input signals by the end device, making available theenergy required for driving the transducer elements by transmission fromthe end device via a contactless interface through inductive coupling,and the end device derives an exact position of the data carrier on thedisplay screen through evaluation of the input signals, and performing,via the at least one or set of transducer elements, a signal exchangefrom the display screen to the data carrier, by test signal sequencesbeing generated location-dependently through the display screen, saidsequences being detected by the transducer elements operated as sensors,and evaluated as input signals through the data carrier.
 2. The methodaccording to claim 1, wherein the data carrier comprises a contact-typeinterface having several contact pads which are employed as part of theat least one or set of capacitive transducer elements on which thesignals are generated for the display screen.
 3. The method according toclaim 1, wherein for driving the transducer elements a drive apparatuscauses changes of charge in an order of magnitude of 1 pF to an order ofmagnitude of less than 2 pF on the at least one or set of transducerelements.
 4. The method according claim 1, wherein the data carriercomprises a window element in relation to which the at least one or setof transducer elements are arranged at defined positions on or in thedata carrier, wherein the end device, after deriving the exact positionof the data carrier on the display screen, outputs a content informationitem which is correctly positioned relative to the window element. 5.The method according to claim 1, wherein the signal exchange isperformed from the display screen to the data carrier by the datacarrier being equipped with an acceleration sensor and the displayscreen being intermittently excited to vibrate, the vibrations beingdetected by the acceleration sensor and evaluated as input signalsthrough the data carrier.
 6. The method according to claim 5, whereinthrough the data carrier a transaction information item specific to thetransaction is generated and transferred selectively via the contactlessinterface or the at least one or set of transducer elements to the enddevice, which transfers the transaction data together with thetransaction information item to a server for further processing, inparticular via a secure channel.
 7. The method according to claim 1,wherein for carrying out a security-critical electronic transaction onthe end device, transaction data are transferred to a server, whichforms a transaction number and encrypts the transaction data as an imagewith a key specific to the data carrier and transfers the key to the enddevice together with the transaction data via a separate channel, theimage-encrypted data being displayed on the display screen of the enddevice and a decryption of the image-encrypted data occurs when a windowelement of the data carrier is correctly positioned and superimposedwith the image-encrypted data displayed on the display screen.
 8. Themethod according to claim 7, wherein the transaction data are presentedon the display screen of the end device such that they appear in thewindow element of the data carrier.
 9. The method according to claim 1,wherein for carrying out a security-critical transaction on the enddevice, transaction data are transferred to the data carrier via the atleast one or set of transducer elements.
 10. The method according toclaim 1, wherein a signal transmission from the data carrier to adisplay screen is only possible when a circuit between the data carrierand the end device is closed via the user.
 11. A data carrier forinteraction with an end device, comprising: a transducer arrangementhaving at least one or a set of capacitive transducer elements arrangedon or in the data carrier at defined positions in relation to thegeometry of the data carrier; a contactless interface via which energyis transmitted from the end device through inductive coupling, and adrive apparatus connected to the contactless interface and configuredfor changing the charge state of the capacitive transducer elements in atargeted manner, and wherein the at least one or set of transducerelements is configured to perform a signal exchange from a displayscreen of the end device to the data carrier, by test signal sequencesbeing generated location-dependently through the display screen, saidsequences being detected by the transducer elements operated as sensors,and evaluated as input signals through the data carrier.
 12. The datacarrier according to claim 11, which additionally comprises a windowelement in relation to which the transducer elements are arranged atdefined positions on or in the data carrier.
 13. The data carrieraccording to claim 11, which has a back contact area as well as a switchas a consent apparatus, the switch being connected to the back contactarea and at least one transducer element, with a change of the potentialof the at least one transducer element connected thereto being possible,through actuation of the switch, when a user produces an electricallyconductive connection between back contact area and the end device bysimultaneously touching an outside contact area connected to the displayscreen.
 14. An end device for interaction with a data carrier accordingto claim 11, wherein the end device is configured for deriving an exactposition of the data carrier on the display screen through evaluation ofthe signals of the at least one or set of transducer elements.
 15. Theend device according to claim 14, wherein the end device is configuredfor outputting on the display screen a content information item which iscorrectly positioned relative to a window element of the data carrier.16. The end device according to claim 14, further comprising an outsidecontact area connected electroconductively to the display screen.
 17. Asystem for interaction of a portable data carrier with an end device,comprising: at least one data carrier comprising: a transducerarrangement having at least one or a set of capacitive transducerelements arranged on or in the data carrier at defined positions inrelation to the geometry of the data carrier; a contactless interfacevia which energy is transmitted from the end device through inductivecoupling, and a drive apparatus connected to the contactless interfaceand configured for changing the charge state of the capacitivetransducer elements in a targeted manner, and a back contact area aswell as a switch as a consent apparatus, the switch being connected tothe back contact area and at least one transducer element, with a changeof the potential of the at least one transducer element connectedthereto being possible, through actuation of the switch, when a userproduces an electrically conductive connection between back contact areaand at least one end device by simultaneously touching an outsidecontact area connected to a display screen of the end device; and the atleast one end device wherein the at least one end device is configuredfor deriving an exact position of the data carrier on the display screenthrough evaluation of the signals of the transducer elements.
 18. Amethod for interaction of a portable data carrier with an end device,wherein the data carrier comprises a transducer arrangement having atleast one or a set of capacitive transducer elements arranged on or inthe data carrier at defined positions in relation to the geometry of thedata carrier, and the data carrier is supplied with energy; wherein theend device comprises a capacitive display screen having atouch-sensitive display, wherein the method comprises placing the datacarrier onto the display screen and generating via the capacitivetransducer elements signals picked up and evaluated as input signals bythe end device, making available the energy required for driving thetransducer elements through an internal energy supply of the datacarrier, and the end device derives an exact position of the datacarrier on the display screen through evaluation of the input signals,wherein the data carrier comprises a window element in relation to whichthe at least one or set of transducer elements are arranged at definedpositions on or in the data carrier, wherein the end device, afterderiving the exact position of the data carrier on the display screen,outputs a content information item which is correctly positionedrelative to the window element.
 19. A data carrier for interaction withan end device, comprising: a transducer arrangement having at least oneor a set of capacitive transducer elements arranged on or in the datacarrier at defined positions in relation to the geometry of the datacarrier; a dedicated energy supply, and a drive apparatus connected tothe energy supply and configured for changing the charge state of thecapacitive transducer elements in a targeted manner, wherein the datacarrier has a back contact area as well as a switch as a consentapparatus, the switch being connected to the back contact area and atleast one transducer element, with a change of the potential of the atleast one transducer element connected thereto being possible, throughactuation of the switch, when a user produces an electrically conductiveconnection between back contact area and the end device bysimultaneously touching an outside contact area connected to a displayscreen of the end device.